The present invention relates generally to police radar detectors used in motor vehicles and, more particularly, to a police radar detector which not only detects radar signals incident on a motor vehicle but also determines if detected radar signals are coming from more than one radar signal source and alerts the operator of the motor vehicle of both the radar signals and that one or more sources of radar signals are present.
Radar signals have been commonly used by police for some time to determine the speed of motor vehicles. In response to radar speed monitoring and to signal motor vehicle operators when such monitoring is taking place, police radar detectors have likewise been used for almost a coincident period of time. Currently available radar detectors indicate the presence of radar signals, the frequency band of detected signals and the relative field strength of detected signals.
Widely varying operating procedures for using police radar and the proliferation of other signals assigned to the same frequency bands as police radar has led to the need for police radar detectors which give more information than that provided by currently available radar detectors. For example, two or more police speed monitoring radars may be deployed close to one another such that motorists become complacent after having passed the first unit only to encounter the second. Combinations of mobile and stationary units also may be used in an effort to mask one another and thereby defeat radar detectors.
In addition to the possible variations in police radar signal encounters, there are many different sources of microwave signals in the frequency bands allocated to police radar by the U.S. Federal Communications Commission (FCC) since these bands have also been allocated for transmitters performing other functions. For example, motion-detecting burglar alarms, automatic door openers, and low-power speed measuring devices used in sports also operate in the frequency bands allocated to police radar. Unfortunately, police radar detectors cannot distinguish between signals generated by a police radar transmitter and those generated by other devices which utilize microwave signals within the same frequency bands.
In addition to producing annoying false alarms to the operators of motor vehicles utilizing radar detectors, motorists become accustomed to such radar detector activating signals in certain locations along commonly traveled streets and highways. Police radar units may be deployed by the side of the roadway at these locations since the police also are aware of the local activating signals and that the signals tend to mask their own speed monitoring radar units.
Accordingly, there is a need for an improved police radar detector which can assist the operator of a motor vehicle using the detector to accurately interpret signals generated by the detector to alert the operator of police radar signals incident on the motor vehicle.